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Fe3O4, as a half-metallic ferrimagnetic material, is believed to be one of the most promising materials in spin transport for spintronics. However, fabricating stoichiometric Fe3O4 film is still challenging because the oxidation is hard to control for various preparing methods. In this paper, series of Fe3O4 thin films on Si (100) substrates are grown by sputtering from a Fe3O4 target without oxygen atmosphere at different growth temperature and then extra heat treatment in high vacuum. By combining X-ray diffractometer (XRD), Raman spectrum, X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism, VSM analysis, we see that the structure and magnetic moment of Fe3O4 film are not only related with growth temperature during sputtering, but also refer to the temperature of post-heat treatments. When the growth temperature is lower than 300 °C, the film does not show any XRD diffraction peaks. When the growth temperature increases from 300 to 500 °C, the film shows the (111) texture of Fe3O4 film clearly. However, the other XRD diffraction peaks are observed after post-heat treatment. The saturation magnetization increases with growth temperature and the largest saturation magnetization is 473 emu/cm3 for growth temperature of 450 °C and extra heat treatment, which is close to bulk Fe3O4. Our results suggest that a selectable method can be used to fabricate high magnetic moment of Fe3O4 thin film.

Magnetic dynamic damping is significantly important in determining the relaxation time of magnetic moments and the speed of magnetic memory devices. Here, magnetic dynamic behaviors of permalloy (Py) films capped with gadolinium (Gd) are studied, and the effects of the interface are investigated by the Cu insert layer. For Py/Gd bilayer films, both the saturation magnetization ( ${M}_{s}$ ) and the surface anisotropy constant ( ${K}_{{\bot }}$ ) are decreased with increasing Gd thickness, while the Gilbert damping ( $\alpha$ ) is enhanced. With the insert of Cu at Py/Gd interface, the above tendencies of ${M}_{s}$ , ${K}_{\bot }$ , and $\alpha $ are suppressed. We attribute these phenomena to the antiferromagnetic coupling between Gd and Py near the interface, which are caused by the magnetic proximity effect (MPE) instead of the spin relaxation in the rare earth Gd themselves.

We investigate the current induced depinning of magnetic domain walls (DWs) trapped at the kinks in a patterned Py nanowire with two-kink zigzag shape on Si/SiO2 substrate. By injecting pulse current with varying amplitude, two threshold current densities with a slight difference of around $6 \times 10^{10}$ A m−2 have been determined according to the different depinning process. The smaller threshold current density corresponds to the depinning of a single DW which is always the first DW facing to the electron flow. This fact indicates that the different pinning potential caused by the structural asymmetry is not the key to determine which DW is to depin. Micromagnetic simulations provide evidence that the specific current-driven behavior of the vortex DW might account for the single depinning process. The larger threshold corresponds to the simultaneous depinning of two DWs which has been commonly observed in a variety of shaped nanowires. This asynchronous depinning phenomenon provides the possibility of the selective DW depinning in the future logic devices.

Chromium tellurides have triggered tremendous investigations in physics and materials science, where their unique properties offer excellent opportunities for spintronic applications. Here, we report anisotropic magnetoresistance (AMR) of ferromagnetic CrTe single crystal flake grown by chemical vapor deposition. An individual hexagonal flake exhibits an easy magnetization axis along its normal direction, and cooling from room temperature to low temperature, its electrical resistance measured with the magnetization parallel to current geometry is larger than that for the perpendicular to the current geometry, indicating the presence of an AMR behavior. The AMR ratio has been found to increase with decreasing temperature and is 5.2% at 5 K, comparable with general magnetic transition metal and alloy. This suggests CrTe single crystal flake to be a promising magnetic material for spintronics applications.

Using the vibrating sample magnetometer and ex situ vector network analyzer ferromagnetic resonance, the static and dynamic magnetic properties of Tb (4 nm)/Cr ( t Cr )/Ni 80 Fe 20 (12 nm) trilayers with different thickness of Cr layer (from 0.2 to 4.0 nm) were investigated comparing with those of Ni 80 Fe 20 film. From the results of in-plane static magnetic hysteresis loops, we analyzed the soft magnetic properties and in-plane anisotropy, along with obtaining the saturation magnetization ( M s ) which shows no obvious reducing and a modulation akin to RKKY coupling. By fitting the relationship of resonance field and linewidth versus resonance frequency, the effective magnetization 4π M eff , gyromagnetic ratio γ , and effective damping coefficient ( α eff ) were extracted. It is worthwhile to mention that the inserting of ultrathin Cr layer (0.2 nm) enhanced the above parameters obviously, which then backed down towards their values in Ni 80 Fe 20 film with increasing the thickness of Cr layer as a result of the weakening magnetic proximity effect and the decreasing spin-pumping effect in trilayers. Finally, they became flattening with the Cr layer thicker than 1 nm where oscillations are also observed in the value of γ and α eff. Interestingly, the oscillations in α eff and γ are consistent with each other, which implies the damping mechanism mainly related to the spin-orbit coupling originating from the indirect interaction between Tb and Ni 80 Fe 20 . In addition, the inhomogeneous broadening (Δ H 0 ) were determined to be very small which further ascertain the accurate of the α eff .

The strong (111)-textured ZnxFe3−xO4 thin films were grown on SiO2-terminated silicon substrates using pulsed laser deposition. X-ray diffraction and high resolution transmission electron microscopy clearly show the column growth structure along the film thickness direction in [111] crystalline orientation for every grain column. With the introduction of texture induced magnetic anisotropy in the free energy density model, we quantitatively determined the doping effect on the various anisotropies in (111)-textured ZnxFe3−xO4 films. The mechanisms of ferromagnetic resonance linewidth of ZnxFe3−xO4 thin films are investigated by the theoretical fitting, in which considering the contributions from intrinsic spin-orbit coupling, extrinsic compositions from two-magnon scattering and inhomogeneous broadening. It is found that the Gilbert damping coefficient α increases with increasing Zn substitution x from 0 to 0.3, indicating that the spin-orbit coupling of the ZnxFe3−xO4 thin films increases with the introduction of Zn impurities.

Ferromagnet/two-dimensional transition-metal dichalcogenide (FM/2D TMD) interfaces provide attractive opportunities to push magnetic information storage to the atomically thin limit. Existing work has focused on FMs contacted with mechanically exfoliated or chemically vapor-deposition-grown TMDs, where clean interfaces cannot be guaranteed. Here, we report a reliable way to achieve contamination-free interfaces between ferromagnetic CoFeB and molecular-beam epitaxial MoSe2. We show a spin reorientation arising from the interface, leading to a perpendicular magnetic anisotropy (PMA), and reveal the CoFeB/2D MoSe2 interface allowing for the PMA development in a broader CoFeB thickness-range than common systems such as CoFeB/MgO. Using X-ray magnetic circular dichroism analysis, we attribute generation of this PMA to interfacial d-d hybridization and deduce a general rule to enhance its magnitude. We also demonstrate favorable magnetic softness and considerable magnetic moment preserved at the interface and theoretically predict the interfacial band matching for spin filtering. Our work highlights the CoFeB/2D MoSe2 interface as a promising platform for examination of TMD-based spintronic applications and might stimulate further development with other combinations of FM/2D TMD interfaces.

Interfacial effect of amorphous cobalt-iron-boron (Co60Fe20B20) films deposited on GaAs(001) by DC magnetron-sputtering has been precisely studied. In-plane uniaxial magnetic anisotropy (UMA) as a significant magnetic property has been found in Co60Fe20B20/GaAs heterostructure and the UMA field (Hu) of (∼75 Oe) is achieved. Magnetic Schottky barrier contact has been achieved by current-voltage (I–V) characteristic through the interface with a barrier height of 0.72 eV, which is an appropriate for tunneling injection of spin current from ferromagnet to semiconductors in spin-injection devices.

Magnonic devices are promising alternatives to conventional charge-current-driven spintronic devices. As the basic unit of spintronic devices, the spin valve is of limited use in magnonics because its dynamics is rarely studied. Here, we investigate the interlayer transmission of magnons in dynamic spin valve structures using the time-resolved magneto-optical Kerr effect. Interaction between magnons and the interfacial dissipation are studied by comparing three samples with different spin valve structures. Magnons with different intrinsic frequencies have strong interactions. In contrast, magnons with similar intrinsic frequencies have relatively weak interactions. Interfacial dissipations of magnons are increased by rare earth insertion, which can reduce the interactions between magnons indirectly. This work extends the application of spin valve structures to magnonic devices beyond their conventional use.

The Tb(4 nm)/Cr( ${t}$ nm)/Fe(5 nm) trilayers with different thicknesses of Cr layer have been investigated by X-ray diffraction, vibrating sample magnetometer, and ferromagnetic resonance. When Cr is thinner than 1.8 nm, the ferromagnetic coupling of Tb and Fe leads to higher saturation magnetization ( $M_{s}$ ) than that of Fe(5 nm) film. On the other hand, the Gilbert damping constant $\alpha $ in all the trilayers have been found to exceed the magnitude of the Fe. In particular, when Cr layer is 1 nm thick, $\alpha $ increases by 38% and $M_{s}$ is increased by 6%; when Cr layer is 4 nm thick, $\alpha $ is increased by 46%, while $M_{s}$ is only decreased by 5%. Accordingly, we have demonstrated a way for enhancing damping and magnetic moment simultaneously in the Tb(4 nm)/Cr( ${t}$ nm)/Fe(5 nm) trilayers.

A 3.5 nm amorphous CoFeB film was sputtered on GaAs (001) wafer substrate without applying magnetic field during deposition, and a significant in-plane uniaxial magnetic anisotropy (UMA) field (Hu) of about 300 Oe could be achieved. To precisely determine the intrinsic Gilbert damping constant (α) of this film, both ferromagnetic resonance (FMR) and time-resolved magneto-optical Kerr effect (TRMOKE) techniques were utilized. With good fitting of the dynamic spectra of FMR and TRMOKE, α is calculated to be 0.010 and 0.013, respectively. Obviously, the latter is 30% larger than the former, which is due to the transient heating effect during the TRMOKE measurement. In comparison with ordinary amorphous CoFeB films with negligible magnetic anisotropies, α is enhanced significantly in the CoFeB/GaAs(001) film, which may be mainly resulted from the enhanced spin-orbit coupling induced by the CoFeB/GaAs interface. However, the significant in-plane UMA plays minor role in the enhancement of α.

Fe3O4 particles with uniform size, regular shape and good dispersibility are prepared by solvothermal methods. The size of Fe3O4 particles and their magnetic properties can be adjusted during synthesis. Fe3O4@SiO2 composite magnetic particles with layers of mesoporous SiO2 structure are assembled by improved Stöber method. The different shell thickness of SiO2 layer can be adjusted from 35∼150 nm using multi-coating by changing the content of TEOS to form Fe3O4@nSiO2@mSiO2. The Mössbauer spectra show that Fe3O4 particles are almost stoichiometric. However, it is found that the coverage of SiO2 have a significant effect on the occupation of Fe ions in Fe3O4 particles. Peroxidation appears in Fe3O4@SiO2 composite magnetic particles, which might be caused by oxygen in SiO2 layer during wrapping process.

The mechanism of the magnetic properties on the Zn2+ substituted Fe3O4 film have been investigated based on first principle calculations. It is found that the surface effect plays an important role in the occupation of Zn ion, and in turn changes the magnetic moment. It may also destroy the half metallic behavior of Fe3O4 film even if the Zn2+ concentration only is one Zn2+ per unit cell (4%), which is different from that in bulk material.

Focusing on the Ni80Fe20 (Py)/Nd-Cu bilayers, the magnetization dynamic damping from spin pumping effect is investigated systematically by doping itinerant Cu in rear earth metal Nd. Various Ta/Py/Nd1-xCux/Ta/Si films with x = 0%, 16%, 38%, 46% and 58% are prepared by magnetron sputtering. For every content of Cu, the thickness of Nd-Cu layer is changed from 1 nm to 32 nm. The damping coefficient increases with increasing the thickness of Nd-Cu layer, which shows the trend of the spin pumping behavior. Also, with increasing Cu concentration in the Nd-Cu layer, the damping coefficient decreases, implying that the spin-orbit coupling in Nd-Cu layer is indeed cut down by high itinerant of Cu dopants. It is interesting that the spin diffusion length (λSD) in the Nd-Cu layer for different Cu dopants is not found to increase monotonously.

Single-crystal Fe dot arrays with the lateral size varying from 400 nm to 50 nm are fabricated by focused ion beam (FIB) direct writing from a single-crystalline 10 monolayer (ML) Fe (100) continuous thin film grown on GaAs substrate. The Kerr hysteresis loops of both dot arrays and continuous thin film are measured by focused magnetooptical Kerr effect (MOKE) measurements along four major crystal directions: [0-11] [010] [011] and [001]. It is found that the in-plane uniaxial anisotropy has been greatly reduced down to zero in the dot arrays when the size is less than 150 nm. The micromagnetic simulations confirm the reduction of this intrinsic in-plane uniaxial anisotropy in the patterned dots by separating the effect of the shape anisotropy. The experimental and simulation results further indicate an additional magnetic uniaxial anisotropy along the [010] direction.

Magnetic anisotropies of Fe/MgO/GaAs(100) hybrid structure with two different nonmagnetic capping materials, Au and MgO have been studied by ferromagnetic resonance (FMR). A uniaxial anisotropy, unexpected from the crystal structure was observed in the ultrathin films for both capping materials. Its global easy axis is along [0-11] direction while two (010) directions are equally magnetic hard regardless of the overlayer material. The in-plane uniaxial anisotropy (in-plane cubic anisotropy) of the Au capped samples is stronger (weaker) than that of the MgO capped ones within the range of t Fe = 7.1 to 28 ML. This suggests that the MgO overlayer suppresses the uniaxial anisotropy faster than the Au overlayer.

Using micromagnetic simulation, we investigate the current-induced multiple domain wall motion (CIDWM) in zigzag nanowires with different bar angles (θ=90°, 120° and 150°). Two dynamic processes of single DWM and double DWM are found in different regimes of current density identified by two thresholds in all zigzag nanowires. The decreasing threshold current is found in the zigzag nanowires with increased bar angles, indicating the angular-dependence of the magnetic pinning. This work suggests a possibility of manipulating the single/multiple DWM in future DW devices by introducing the shape anisotropy.

The current-induced motion of magnetic domain walls (DWs) confined to nanostructures is of great interest for fundamental studies as well as for technological applications in spintronic devices. Here, we present magnetic images showing the depinning properties of pulse-current-driven domain walls in well-shaped Permalloy nanowires obtained using photoemission electron microscopy combined with x-ray magnetic circular dichroism. In the vicinity of the threshold current density (Jth = 4.2 × 1011 A.m−2) for the DW motion, discontinuous DW depinning and motion have been observed as a sequence of “Barkhausen jumps”. A one-dimensional analytical model with a piecewise parabolic pinning potential has been introduced to reproduce the DW hopping between two nearest neighbour sites, which reveals the dynamical nature of the current-driven DW motion in the depinning regime.

Previous studies on epitaxial Fe3O4 rings in the context of spin-transfer torque effect have revealed complicated and undesirable domain structures, attributed to the intrinsic fourfold magnetocrystalline anisotropy in the ferrite. In this Letter, we report a viable solution to this problem, utilizing a 6-nm-thick epitaxial Fe3O4 thin film on GaAs(100), where the fourfold magnetocrystalline anisotropy is negligible. We demonstrate that in the Fe3O4 planar wires patterned from our thin film, such a unique magnetic anisotropy system has been preserved, and relatively simple magnetic domain configurations compared to those previous reports can be obtained.